1. Field of the Invention
The present invention relates generally to a circuit protector that functions like a circuit breaker to protect a circuit from damage caused by overloading, undesired high temperature, and in particular to a circuit protector that is triggered by high temperature caused by overloading and the likes to open the circuit.
2. Prior Arts
Electricity is one of the most widely used energies in modern societies. Wide applications of electricity can be found in almost all fields, especially in a computerized, information-based society. Also, household electric appliances play a more and more important role in the modern societies. Such appliances are almost powered by electricity. Due to the wide applications of electricity in the modern societies, damage caused by improper use of electricity are often observed, especially fire catastrophes caused by overheating of electrical devices.
To ensure safety of using electrical power, a breaker is added in a home electrical circuit. The breaker is a normally-closed device, which allows for transmission of electrical power therethrough in a regular, normal operation, and automatically opens the home circuit when overloading, over-current, or overheating is detected in order to protect the circuit from damage caused by the overloading. It is also known that some electrical devices feature the same function of opening a circuit when overloaded. Similarly, switches are provided with the same function or a circuit protector for opening the circuit in an overloading condition.
FIGS. 1 and 2 of the attached drawings show a conventional circuit protector, comprising a conductive, resilient plate 201 having a convex shape whereby with a first end fixed to a first contact 202, an opposite, second free end forming a first terminal 203 is bent downward to have the first contact 203 physically engaging a second contact 205 mounted on a second terminal 204 and thus completing a closed circuit loop. The plate 201 features deformation and backward springing when overheated caused by overloading of the circuit. The backward springing makes the free end of the plate 201 disengaging from the second terminal 204, thereby opening the circuit and thus realizing circuit protection, as particularly shown in FIG. 2.
However, the conventional circuit protector suffers several drawbacks. For example, it is hard, if not impossible, to ensure the springing behavior of the resilient plate 21 due to manufacturing tolerance and material defects. Thus, the critical temperature at which the resilient plate 21 starts to spring backward cannot be controlled, which means significant deviation from a rated critical temperature may be observed. Further, the resilient plate 21 is not sensitive to temperature increase, which often results in significant time lag in opening a circuit when the circuit is overloaded. It often occurs in the conventional devices that the deformation of the resilient plate is not well controlled and an incomplete disengagement is observed between the resilient plate and a terminal, which means the circuit is still in an overloaded condition and is not properly protected by the protector. An even troublesome drawback of the conventional device is that, when the plate cools down after disengaging from an overloaded circuit, the plate may get back into contact with the circuit, leading to overloading of the circuit again, if the cause of overloading has not been removed. Repeated engaging and disengaging of the resilient plate with the circuit definitely does no good to the circuit and the electronic/electrical appliances connected thereto and may even cause severe damage to the appliances.